What it really took was going to some play group type events with me. I think we hang out with some pretty smart / educated parents... and that they probably have very bright babies... but he finally saw what other babies her age act like.
Hands on experience is the best teacher. If possible arrange a playdate with a 'normal' agemate and get DH to agree to be the parent in charge while you leave the house. If that doesn't shake the DHs to their cores, I don't know what will.
It's also very important to see what every person on your 'ok to talk about Giftedness' has as a definition of Giftedness, and also what they think they 'know' about giftedness. Often just listening and asking calm simple questions will be enough for other folks to 'air out' their old ideas and see if they themselves think that these ideas are reasonable.
I remember talking with some friends at summer camp, maybe age 11,and someone mentioning that their hair grows faster in the summer. I piped up 'Wow that's counterintutitve because everyone knows that hair is dead brain cells and I would think that during the school years you'd have more turnover, and more hair growth.'
I intantly was horrified, because what I had said sounded so wrong and so stupid. I had just pull a bit of information out of my brain that probably had been told to me by my scary next door neighbor years ago and just got stuck in there.
So have pity on your dear ones. If I thought that hair was made out of dead brain cells for even a moment, then anyone can have any old idea hanging aroung the dark corners that needs a bit of sunlight, right?
Love and More Love,
Grinity